Burette float and drainage aperture

ABSTRACT

The present invention relates to a turbulence minimization apparatus comprising a float and seat assembly adapted to control turbulence and formation of microbubbles in a quantity of contrast media in the burette of a contrast media delivery system. The float includes an upper convex surface providing an impact surface for droplets of contrast media which fall from the inlet of the burette, a lower convex surface for sealing a drainage bore when the volume of contrast media has been substantially drained from the burette, and a predetermined amount of buoyancy. The seat assembly includes a plurality of fluid passageways that allow contrast media to contact the lower convex surface of the float allowing the buoyancy of the float to separate the float from the drainage bore when there is more than a predetermined amount of fluid in the drip chamber.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to contrast media delivery systems. Inmore particular, the present invention relates to a burette float andseat for use with a contrast media delivery system.

2. The Relevant Technology

Patient fluid delivery systems have long been used in medicine to ensurereliable and safe delivery of fluids to patients. Typically, suchdelivery systems include a source of fluid such as an infusate bag orbottle, a patient access apparatus such as a catheter or trocar, anddelivery tubing for conveying the fluid from the source of fluid to thepatient. Some delivery systems also incorporate a burette at one or morepositions in the delivery tubing. A burette typically comprises a clearcylindrical apparatus having a drip chamber of a larger diameter thanthe delivery tubing. The drip chamber of the burette is configured to bepartially filled with fluid while fluid is flowing to the burette. Thedrip chamber of the burette helps eliminate any potential air bubbles inthe delivery line. Air bubbles in the delivery line are dissipated asthe fluid enters the burette and forms droplets. The reservoir alsominimizes air bubbles that can form in the outlet line of the burette asa result of interruption of flow of fluid into the burette.

When the fluid in the fluid source is exhausted, fluid is no longerdelivered to the burette from the inlet tubing. Because fluid is nolonger delivered to the burette, the fluid level in the burette beginsto lower. This allows the practitioner to observe the fluid level in theburette to ascertain whether a replacement fluid source is neededwithout actually observing the fluid level in the fluid source. As longas the volume of fluid in the burette exceeds a certain threshold, fluidcontinues to be delivered to the patient from the outlet of the burette.As a result, the burette provides an amount of time in which fluidcontinues to be delivered to the patient after the fluid source has beendepleted. This allows the practitioner to replace the fluid sourcewithout interrupting the delivery of fluid to the patient.

One problem that has been encountered with the use of burettes relatesto filling of the drip chamber of the burette. Typically as the dripchamber is filled, fluid flowing into the drip chamber from the inlet ofthe burette does not immediately contact the volume of fluid in the dripchamber because the drip chamber is only partially filled with fluid.Instead, the fluid forms droplets which fall from the burette inlet ontothe surface of the fluid volume in the drip chamber. In somecircumstances, when the droplets hit the fluid volume the velocity ofthe droplets may create turbulence or microbubbles in the volume offluid. The formation of microbubbles may be undesirable in somecircumstances where they may be delivered to the vasculature of thepatient.

The formation of microbubbles can be particularly challenging where thefluid being delivered to the patient comprises contrast media. Contrastmedia is utilized to allow imaging equipment such as X-ray or MRI toview the flow of fluids in the patient's vasculature or other bodysystems. Contrast media includes radioactive or isotopic qualities thatpermit the contrast media to be detected by the imaging equipment. Thetypes of materials that are often utilized in contrast media often havemolecular weight and/or a high viscosity. The high viscosity canincrease the number and size of microbubbles while inhibiting themigration of the microbubbles out of the volume of contrast media.

A variety of mechanisms have been developed to minimize the formation ofmicrobubbles. One mechanism comprises a ball or other spherical memberthat is configured to float in the volume of fluid in the burette. Thesize and buoyancy of the ball is configured such that the dropletsstrike the surface of the ball instead of the surface of the volume offluid. This not only slows the velocity of the droplets, but alsoprovides a surface along which the droplets can flow and enter thevolume of fluid.

FIG. 1 illustrates a prior art burette 1 having a float 12 for use witha volume of contrast media 19. In the illustrated embodiment, float 12includes buoyant qualities that permit float 12 to be suspended incontrast media 19 such that a portion of float 12 is positioned abovethe surface of contrast media 19. By being suspended such that a portionof float 12 is above the surface of contrast media 19, float 12 providesan impact surface for droplets entering burette 1. For reasons that willbe explained hereinafter, float 12 is not illustrated floating such thata portion of float 12 is above the surface of the contrast media 19.

In the illustrated embodiment, burette 1 includes a drip chamber 10,float 12, seat 14, outlet 16, and inlet 18. Drip chamber 10 provides areservoir for holding the volume of contrast media 19 in burette 1.Contrast media flows from the contrast media delivery source throughinlet 18, into drip chamber 10, and then exits the burette throughoutlet 16. Typically, the contrast media flowing into drip chamber 10from inlet 18 forms droplets. Float 12 is configured to provide animpact surface for the droplets which prevents direct impact of thedroplets on the surface of the volume of contrast media 19.

When contrast media no longer flows into drip chamber 10 from inlet 18,the level of contrast media 19 in drip chamber 10 begins to lower. Whenthe level of contrast media 19 lowers sufficiently, float 12 contactsseat 14. Seat 14 is formed from the inner surface of the wall of dripchamber 10. Seat 14 is configured to conform to the shape of float 12 toprovide an air tight seal with float 12. By providing an air tight sealbetween seat 14 and float 12, a vacuum effect is created in outlet 16and downstream from burette 1. The vacuum effect stops the flow of fluidto the patient and prevents air from entering into the delivery linedownstream from burette 1. By preventing air from entering into thedelivery line downstream from burette 1, the practitioner need notremove air from the delivery line before resuming the flow of fluids tothe patient. This allows for smooth and efficient replacement of thefluid source allowing the flow of fluid to the patient to resume oncethe fluid level in drip chamber 10 of burette 1 is returned to normallevels.

One problem that is presented by the configuration of float 12 and seat14 relates to the air tight seal created by float 12 and seat 14 and thevacuum effect downstream from float 12 and seat 14. The air tight sealand vacuum effect discourages separation of float 12 from seat 14 asdrip chamber 10 begins to refill with liquid. This can be exacerbated bythe fact that seat 14 is formed from the inner wall of drip chamber 10.Because seat 14 is formed from the inner wall of drip chamber 10, thecontact between seat 14 and float 12 is along much of the bottom surfaceof float 12 making it difficult for contrast media to flow to theunderside of float 12. Because the buoyancy of float 12 results fromcontact between contrast media 19 and the underside of float 12,insufficient buoyancy is created to overcome the vacuum effect whichprevents separation of float 12 and seat 14. Additionally, most or allof the contrast media 19 is primarily in contact with the upper surfaceof float 12 resulting in a downward pressure being exerted on float 12by contrast media 19. The downward force exerted by contrast media 19 onthe upper surface of float 12 also prevents separation between float 12and seat 14.

While float 12 remains in air tight contact with seat 14, flow ofcontrast media 19 to the patient will not resume. To overcome the vacuumeffect and air tight seal between float 12 and seat 14 and in an attemptto resume flow of contrast media 19 to the patient, practitioners mayshake or tap burette 1 in an attempt to dislodge float 12. By dislodgingfloat 12, contrast media 19 can move to the underside of float 12allowing the buoyancy of float 12 to separate from seat 14 and float tothe surface of contrast media 19. However, shaking or tapping of burette1 can result in the additional turbulence in contrast media 19. Theturbulence can create the type of microbubbles which float 12 wasoriginally designed to prevent. Additionally, during the time in whichthe float 12 is covered with a volume of contrast media 19, dropletsfalling from inlet 18 can also create microbubbles in the volume ofcontrast media 19.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a turbulence minimization apparatus foruse with a burette of a contrast media delivery system. The turbulenceminimization apparatus is adapted to control turbulence and formation ofmicrobubbles in a quantity of contrast media in the burette. In oneembodiment of the present invention the turbulence minimizationapparatus comprises a float and a seat assembly. The float includes anupper convex surface and a lower convex surface. The float also has apredetermined amount of buoyancy adapted to facilitate separation of thefloat from the seat assembly when there is more than a predeterminedamount of contrast media in the drip chamber of the burette.

The seat assembly includes a drainage bore and a seat. The seat includesa plurality of fluid passageways that allow contrast media to flowbeneath the float and contact the lower convex surface of the float. Inone embodiment, the seat with the plurality of fluid passagewayscomprises a plurality of projections. The space between the projectionscomprises the fluid passageways. The projections are configured toaccommodate the float such that the float is positioned over thedrainage bore creating an air tight seal with the drainage bore when thevolume of contrast media in the burette falls below a predeterminedlevel. In this manner the float minimizes the introduction of air intothe line downstream from the burette. The projections also allow thecontrast media to flow to the underside of at least a portion of thefloat such that when the level of the contrast media reaches apredetermined level, the buoyancy of the float overcomes any potentialvacuum effect separating the float from the drainage bore.

According to one embodiment of the present invention the float is formedfrom first and second convex members that form an air cavity whencombined. According to another embodiment of the present invention, thefloat includes an upper convex surface and a lower non-convex surface.According to another embodiment of the present invention, the seatassembly includes a drainage bore and a seat member. According to oneembodiment of the present invention, the seat member allows contrastmedia to flow to the underside of at least a portion of the float suchthat when the level of the contrast media reaches a predetermined level,the buoyancy of the float overcomes any potential vacuum effect betweenthe drainage bore and the float. In one embodiment the seat membercomprises a plurality of projections that support the float whileallowing contrast media to contact the lower surface of the float. Inanother embodiment, the fluid passageways comprise channels, voids, orapertures that allow contrast media to contact the underside of thefloat.

These and other objects and features of the present invention willbecome more fully apparent from the following description and appendedclaims, or may be learned by the practice of the invention as set forthhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the appended drawings. It is appreciated that thesedrawings depict only typical embodiments of the invention and aretherefore not to be considered limiting of its scope. The invention willbe described and explained with additional specificity and detailthrough the use of the accompanying drawings in which:

FIG. 1 is a prior art depiction of a burette of a contrast mediadelivery system having a float.

FIG. 2 illustrates a turbulence minimization apparatus having a floatand seat assembly for use with a burette according to one exemplaryembodiment of the present invention.

FIG. 3 is a perspective view of the float and seat assembly of FIG. 2.

FIG. 4 is a partial cross-sectional view of the float and seat assemblyof FIG. 2.

FIG. 5 is a front cut-away view of the burette of FIG. 2 illustratingthe float positioned on the seat assembly when the level of contrastmedia is below a predetermined level.

FIG. 6 is a front cut-away view of the burette illustrating the mannerin which the seat assembly allows contrast media to flow to the lowersurface of the float.

DETAILED DESCRIPTION

The present invention relates to a turbulence minimization apparatus foruse with a burette of a contrast media delivery system. The turbulenceminimization apparatus is adapted to control turbulence and formation ofmicrobubbles in a quantity of contrast media in the burette. In oneembodiment of the present invention the turbulence minimizationapparatus comprises a float and a seat assembly. The float includes anupper convex surface and a lower convex surface. The float also has apredetermined amount of buoyancy adapted to facilitate separation of thefloat from the seat assembly when there is more than a predeterminedamount of contrast media in the drip chamber of the burette.

The seat assembly includes a drainage bore and a seat. The seat includesa plurality of fluid passageways that allow contrast media to flowbeneath the float and contact the lower convex surface of the float. Inone embodiment, the seat comprises a plurality of projections. The spacebetween the projections comprises the fluid passageways of the seat. Theprojections are configured to accommodate the float such that the floatis positioned over the drainage bore creating an air tight seal with thedrainage bore when the volume of contrast media in the burette fallsbelow a predetermined level. In this manner the float minimizes theintroduction of air into the line downstream from the burette. Theprojections also allow the contrast media to flow to the underside of atleast a portion of the float such that when the level of the contrastmedia reaches a predetermined level, the buoyancy of the float overcomesany potential vacuum effect allowing the float to separate from thedrainage bore.

According to one embodiment of the present invention the float is formedfrom first and second convex members that form an air cavity whencombined. According to another embodiment of the present invention, thefloat includes an upper convex surface and a lower non-convex surface.According to another embodiment of the present invention, the seatassembly includes a drainage bore and a seat member. According to oneembodiment of the present invention, the seat member allows contrastmedia to flow to the underside of at least a portion of the float suchthat when the level of the contrast media reaches a predetermined level,the buoyancy of the float overcomes any potential vacuum effect betweenthe drainage bore and the float. In one embodiment the seat membercomprises a plurality of projections that support the float whileallowing contrast media to contact the lower surface of the float. Inanother embodiment, the fluid passageways comprise channels, voids, orapertures that allow contrast media to contact the underside of thefloat. According to another embodiment, the curved configuration of thelower surface of the float minimizes the entrapment of air in thechamber that could otherwise be released into the outlet of burette andeventually the delivery line.

FIG. 2 illustrates a turbulence minimization apparatus 118 utilized inconnection with burette 100 of a contrast media delivery system.Turbulence minimization apparatus 118 controls turbulence and theformation of microbubbles in a quantity of contrast media 112 in burette100 of the contrast media delivery system. In the illustratedembodiment, turbulence minimization apparatus 118 comprises a float 120and a seat assembly 140. Float 120 provides a contact surface fordroplets falling from an inlet 110 of burette 100. Seat assembly 140allows contrast media to flow to the underside of at least a portion offloat 120 such that when the level of the contrast media reaches apredetermined level, the buoyancy of float 120 overcomes any potentialvacuum effect downstream from float 120. This allows the buoyancy offloat 120 to create separation between float 120 and seat assembly 140when there is more than a predetermined amount of contrast media in theburette 100. Turbulence minimization apparatus 118 is one example of avalve assembly.

In the illustrated embodiment, burette 100 includes a drip chamber 106,an outlet 108, and an inlet 110. Drip chamber 106 is configured to holda volume of contrast media 112. According to one embodiment of thepresent invention, a drip chamber wall 104 is comprised of a transparentor semi-transparent material which allows the user to view the level ofcontrast media 112 in drip chamber 106. Drip chamber wall 104 definesthe size and configuration of drip chamber 106. Drip chamber 106comprises the interior lumen of barrel 102 in which contrast media 112is positioned. In the illustrated embodiment, drip chamber 106 issubstantially cylindrical along the length of barrel 102.

Outlet 108 is positioned at the bottom of burette 100 in fluidcommunication with outlet line 114. Inlet 110 is positioned at the topof burette 100 in fluid communication with inlet line 116. In theillustrated embodiment, contrast media flows from the contrast mediasource, such as a bag or bottle, into inlet line 116. From inlet line116 the contrast media flows into drip chamber 106 through inlet 110.Typically, as the contrast media enters drip chamber 106 from inlet 110,it forms droplets that fall from inlet 110 into drip chamber 106.

Float 120 is positioned in drip chamber 106. Float 120 includes apredetermined amount of buoyancy which positions the upper surface offloat 120 above the surface of the volume of contrast media 112. Float120 provides an impact surface for the droplets of contrast mediafalling from inlet 110. As the droplets of contrast media strike float120, the velocity of the droplets is substantially reduced. The dropletscan then flow along the upper surface of float 120 and into the volumeof contrast media 112. In the illustrated embodiment, the diameter offloat 120 is sufficiently smaller than the diameter of drip chamber 106to allow unobstructed flow of contrast media from the upper surface offloat 120 into the volume of contrast media 112. Additionally, thecurved configuration of the lower surface of the float 120 minimizes theentrapment of air in the chamber 10 that could otherwise be releasedinto the outlet 108 of burette and eventually the outlet line 114.

The volume of contrast media 112 in drip chamber 106 flows into adrainage bore of seat assembly 140, through outlet 108, and into outletline 114. From outlet line 114 the contrast media can be infused intothe patient. When the volume of contrast media in the contrast mediasource is exhausted, contrast media no longer flows into drip chamber106 from inlet 110. Where contrast media from the contrast media sourceis no longer filling drip chamber 106, as long as the volume of contrastmedia 112 continues to flow into outlet line 114, the level of thevolume of contrast media 112 will begin to lower. As the level of thevolume of contrast media 112 begins to lower, the positioning of float120 also begins to lower. In this manner, float 120 can be utilized asan indicator of the level of the volume of contrast media 112 in dripchamber 106. The lowering of float 120 signals to the practitioner thatthe source of contrast media is exhausted and needs to be replaced. Thevolume of contrast media 112 in drip chamber 106 maintains the flow ofcontrast media to the patient even where the contrast media source isexhausted and contrast media is no longer filling burette 100. Thisprovides the practitioner with time to replace the source of contrastmedia after the contrast media is no longer flowing into burette 100.

When the volume of contrast media 112 in drip chamber 106 issubstantially emptied from drip chamber 106, float 120 contacts and issupported by seat assembly 140. The configuration of the lower surfaceof float 120 conforms to the configuration of the upper surface of seatassembly 140 such that seat assembly 140 accommodates and provides adesired positioning of float 120. In the illustrated embodiment, thelower surface of float 120 comprises a convex surface while the uppersurface of seat assembly 140 comprises a concave surface. The lowersurface of float 120 is configured to provide an air tight seal with thedrainage bore of the seat assembly. The configuration of float 120 andseat assembly 140 will be discussed in greater detail with reference toFIGS. 3-6.

As will be appreciated by those skilled in the art, a variety of typesand configurations of turbulence minimization apparatuses can beutilized with a variety of types and configurations of burettes withoutdeparting from the scope and spirit of the present invention. Forexample, in one embodiment a burette that is non-cylindrical inconfiguration is utilized. In another embodiment, at least one of theupper or lower surfaces of the float is substantially convex inconfiguration. In yet another embodiment, a secondary assembly such as adiffusion plate that controls movement of droplets of contrast media isutilized. In another embodiment, the turbulence minimization apparatusis utilized with a fluid delivery system other than a contrast mediadelivery system.

FIG. 3 is a close-up perspective view of float 120 and seat assembly 140of turbulence minimization apparatus 118. In the illustrated embodiment,float 120 comprises an upper convex surface 124, an outercircumferential rim 126, a lower convex surface 134, and an outercircumferential rim 136. Upper convex surface 124 provides a contactsurface for droplets of contrast media falling from inlet 110 of burette100 (see FIG. 2). Lower convex surface 134 is positioned on float 120opposite upper convex surface 124. Lower convex surface 134 isconfigured to contact an upper surface of seat assembly 140.

Outer circumferential rim 126 is positioned adjacent upper convexsurface 124. Outer circumferential rim 136 is positioned adjacent lowerconvex surface 134. Outer circumferential rim 126 is coupled to outercircumferential rim 136. Outer circumferential rim 126 and outercircumferential rim 136 provide a desired amount of displacement betweenupper convex surface 124 and lower convex surface 134. In theillustrated embodiment, the degree of curvature of upper convex surface124 and lower convex surface 134 and the amount of displacement providedby outer circumferential rim 126 and outer circumferential rim 136results in a disk-like configuration of float 120.

The disk-like configuration of float 120 minimizes flipping of float 120which would otherwise position upper convex surface 124 below thesurface of the volume of contrast media 112. In the illustratedembodiment, the curvature of upper convex surface 124 is similar to thecurvature of the lower convex surface 134. This allows both the upperconvex surface 124 and lower convex surface 134 to perform similarlyregardless of the orientation of float 120 in the event that float 120is flipped upside down. The disk-like configuration of float 120 alsoprovides a greater surface area of both the upper convex surface 124 andlower convex surface 134 relative to the overall volume of float 120.The surface area of upper convex surface 124 provides a greater contactarea for falling droplets. The surface area and degree of curvature oflower convex surface 134 increases the buoyancy of float 120 relative tothe overall volume of float 120.

In the illustrated embodiment, float 120 is formed from a deformablematerial that allows lower convex surface 134 of float 120 to conform tothe surface of a circumferential contact surface 146 of drainage bore142 to create a fluid tight seal with a drainage bore of seat assembly140. As will be appreciated by those skilled in the art, float 120 canbe constructed utilizing a number of materials without departing fromthe scope and spirit of the present invention. For example, in oneembodiment the float is constructed from a soft and pliable materialsuch as silicone or urethane which has a shore hardness of between 20 Aand 40 A and is coated with a parylene or other surface treatment. Inanother embodiment, the float is constructed from a material selectedfrom rubberized foam, neoprene, isoprene, thermoplastics, elastomericplastics, rubbers, or other materials having a desired amount ofbuoyancy either alone, in combination with air pockets, or incombination with other buoyant materials. As will be appreciated bythose skilled in the art, materials having varying shore hardnessoutside of the range of 20 A and 40 A and different material propertiesfrom the above referenced materials can also be utilized. Additionally,the seat can be adapted to have soft and pliable properties toaccommodate floats having more rigid material properties.

As will be appreciated by those skilled in the art, a variety of typesand configurations of floats can be utilized without departing from thescope and spirit of the present invention. For example, in oneembodiment the outer circumferential rims provide a greater displacementbetween the upper convex surface and the lower convex surface. Inanother embodiment, one or both of the upper and lower convex surfaceshave a greater or lesser degree of curvature. In yet another embodiment,one or both of the upper and lower surfaces are non-convex inconfiguration. In another embodiment, the lower convex surface of thefloat is coated with a pliable material to facilitate the fluid tightseal with the drainage bore of the seat assembly.

In the illustrated embodiment, seat assembly 140 includes a drainagebore 142 and a seat 150. Drainage bore 142 provides a conduit for thevolume of contrast media flowing from drip chamber 106 of burette 100(see FIG. 2). Drainage bore 142 is positioned in fluid communicationwith outlet 108 of burette 100 (see FIG. 2). Drainage bore 142 ispositioned at the center of seat assembly 140. Drainage bore 142includes a wall 144 and a circumferential contact surface 146. Wall 144comprises the outer boundary of drainage bore 142. Wall 144 extends thelength of drainage bore 142 from the bottom of the burette to the top ofcircumferential contact surface 146. Circumferential contact surface 146is positioned at the top of wall 144. Circumferential contact surface146 is configured to provide an airtight seal when positioned in contactwith float 120.

Seat 150 is configured to accommodate the lower convex surface 134 offloat 120. In the illustrated embodiment, seat 150 includes a pluralityof projections 152 a-h. The plurality of projections 152 a-h provide adesired amount of displacement between the bottom of the burette and thelower convex surface 134 of float 120. Additionally, projections 152 a-hproperly position float 120 relative to circumferential contact surface146 to provide an air tight seal between float 120 and circumferentialcontact surface 146.

Projections 152 a-h include contact surfaces 154 a-h. Contact surfaces154 a-h collectively form an upper contact surface of seat 150. In theillustrated embodiment, contact surfaces 154 a-h form a concave surfacefor accommodating lower convex surface 134 of float 120. The portions ofcontact surfaces 154 a-h adjacent circumferential contact surface 146 ofdrainage bore 142 are at substantially the same elevation ofcircumferential contact surface 146. As a result, when lower convexsurface 134 of float 120 is in contact with contact surfaces 154 a-h ofprojections 152 a-h, lower convex surface 134 contacts the entirecircumference of circumferential contact surface 146 providing an airtight seal between circumferential contact surface 146 and lower convexsurface 134.

The configuration of projections 152 a-h allows the contrast media toflow between projections 152 a-h and into contact with lower convexsurface 134 of float 120. In the illustrated embodiment, the spacesbetween projections 152 a-h comprise fluid passageways that allow thecontrast media to contact the lower convex surface 134 of float 120. Asa result, where the contrast media begins to fill the chamber of theburette, the contrast media contacts and provides a buoyant force onlower convex surface 134 of float 120. In the illustrated embodiment,the buoyancy of float 120 is selected to be greater than the forcevector exerted on float 120 resulting from the combination of the vacuumeffect in drainage bore 142 and the force vector resulting from anyfluid positioned above float 120. When the level of the contrast mediais raised sufficiently, the amount of buoyancy of float 120 exceeds anyvacuum effect between lower convex surface 134 and circumferentialcontact surface 146. As a result, lower convex surface 134 separatesfrom circumferential contact surface 146 and the flow of fluid throughdrainage bore 142 to the outlet of the burette can resume.

As will be appreciated by those skilled in the art, a variety of typesand configurations of seat assemblies can be utilized without departingfrom the scope and spirit of the present invention. For example, avariety of types, numbers, and configurations of projections of the seatcan be utilized. In one embodiment, a circumferential member is attachedto the outer edges at the top of the projections. In another embodiment,the seat of the seat assembly comprises a concave surface with aplurality of fluid passageways, voids, channels, or apertures forallowing contact between the contrast media and the lower convex surfaceof the float. In another embodiment, the drainage bore does not includea wall and the circumferential contact surface is positioned at the sameelevation as the bottom of the chamber of the burette. In anotherembodiment, the projections of the seat extend from the drip chamberwall rather from the bottom of the burette.

FIG. 4 is a cut-away view of float 120 and seat assembly 140 accordingto one embodiment of the present invention. In the illustratedembodiment, float 120 comprises an upper portion 122, an air cavity 130,and a lower portion 132. Upper portion 122 is coupled to lower portion132 to form air cavity 130. Upper portion 122 includes an upper convexsurface 124, an outer circumferential rim 126, and an upper columnmember 128. Upper convex surface 124 provides an impact surface fordroplets of contrast media falling from the inlet of the burette. Outercircumferential rim 126 provides a mechanism for coupling upper portion122 to lower portion 132. Upper column member 128 provides internalstructural support for the center of upper portion 122. Upper columnmember 128 also provides a coupling mechanism for securing upper portion122 to lower portion 132.

Lower portion 132 includes a lower convex surface 134, an outercircumferential rim 136, and a lower column member 138. Lower convexsurface 134 is configured to be accommodated by seat 150 of seatassembly 140 when there is less than a predetermined amount of contrastmedia in the drip chamber. Outer circumferential rim 136 provides amechanism for coupling lower portion 132 to upper portion 122. Lowercolumn member 138 provides internal structural support for the center oflower portion 132. Lower column member 138 also provides a couplingmechanism for securing upper portion 122 to lower portion 132.

As will be appreciated by those skilled in the art, a variety of typesand configurations of floats can be utilized without departing from thescope and spirit of the present invention. For example, in oneembodiment, the buoyancy of the float is provided by the buoyancy of thematerials from which the float is constructed. In another embodiment,the upper portion and lower portion are sufficiently rigid to obviatethe need for one or more column members. In yet another embodiment, thefloat is formed from a single uniform piece of material.

In the illustrated embodiment a cut-away view of seat assembly 140 isshown. It can be seen that the configuration of wall 144 extendsdrainage bore 142 to the top of circumferential contact surface 146. Theconfiguration of circumferential contact surface 146 and the contactsurfaces (see i.e. 154 a, e) of the projections (see i.e. 152 a, e)provides a fluid tight seal between circumferential contact surface 146and lower convex surface 134 when float 120 is positioned on seat 150.

FIG. 5 is a cut-away side view of burette 100 illustrating thejuxtaposition of float 120 relative to seat assembly 140 when the volumeof contrast media has been drained from drip chamber 106 of burette 100.In the illustrated embodiment, lower convex surface 134 of float 120 ispositioned in contact with the contact surfaces (see e.g. 154 a) of theprojections (see e.g. 152 a) of seat 150. As previously discussed, whenlower convex surface 134 is in contact with seat 150, lower convexsurface 134 forms an air tight seal with circumferential contact surface146 (see FIG. 4). The air tight seal between lower convex surface 134and circumferential contact surface 146 (see FIG. 4) and the siphoneffect of contrast media 112 in outlet 108 and outlet line 114 creates avacuum effect in outlet 108 and outlet line 114 (see also FIG. 4). Thevacuum effect in outlet 108 and outlet line 114 prevents additional flowof the remaining volume of contrast media 112 from outlet line 114 tothe patient. This prevents migration of air into outlet line 114 whenthe volume of contrast media in drip chamber 106 in burette 100 isexhausted. By preventing migration of air into outlet line 114, thepractitioner need not remove air that would otherwise form in outletline 114 when the volume of contrast media in drip chamber 106 isreturned to normal levels.

FIG. 6 is a cut-away side view of burette 100 illustrating thejuxtaposition of float 120 relative to seat assembly 140 when contrastmedia is again introduced into drip chamber 106 of burette 100. In theillustrated embodiment, contrast media flows from inlet line 116 intodrip chamber 106 through inlet 110. As the contrast media flows intodrip chamber 106 it forms droplets which fall onto upper convex surface124 of float 120. Once the droplets strike upper convex surface 124 offloat 120, the droplets of contrast media flow from the upper convexsurface 124 of float 120 into the volume of contrast media in dripchamber 106.

As the volume of contrast media in drip chamber 106 increases, theconfiguration of the projections (see e.g. 152 a) and the fluid pathwayscreated by the projections allows contrast media to flow beneath andinto contact with at least a portion of lower convex surface 134 offloat 120. As the volume of contrast media continues to increase, thebuoyancy of float 120 overcomes any vacuum effect maintaining thecontact between float 120 and seat assembly 140. As a result, float 120separates from seat assembly 140 resuming the flow of contrast mediafrom drainage bore 142 (see FIG. 4), through outlet 108, outlet line114, and into the patient.

As will be appreciated by those skilled in the art, a variety of typesand configurations of turbulence minimization apparatuses can beutilized without departing from the scope and spirit of the presentinvention. For example, in one embodiment the degree of curvature of thelower convex surface and the configuration of the seat positions thedrainage bore at the level of the bottom of the burette. In anotherembodiment, the lower surface of the float is concave while the uppersurface of the seat is convex in configuration. In another embodiment,the float includes a lower relief surface which allows the contrastmedia to contact a portion of the lower surface of the float.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A valve assembly for use with a burette of a fluid delivery system,the burette having an inlet for providing the inflow of contrast mediato the burette, a drip chamber for containing a volume of contrast mediaand a volume of air for permitting dissipation of air bubbles in thecontrast media entering the drip chamber from tubing upstream from theburette, and an outlet for allowing passage of the volume of contrastmedia from the drip chamber to portions of the fluid delivery systemdownstream from the burette, the valve assembly comprising; a floatpositioned in the drip chamber of the burette, the float having an upperconvex surface, a lower convex surface, and an outer circumferential rimpositioned between the upper convex surface and the lower convex surfaceproviding a desired amount of displacement between the upper convexsurface and the lower convex surface, the juxtaposition of the upperconvex surface, the lower convex surface and the outer circumferentialrim forming a disk shaped configuration of the float such that the sideprofile of the float forms a substantially elliptical shape rather thana spherical shape or cylindrical, the float having a predeterminedamount of buoyancy, the float being adapted to provide an impact surfacefor droplets of fluid passing from the inlet into the drip chamber whilepermitting the passage of fluid from the upper surface of the float tothe lower surface of the float; and a seat configured to accommodate andprovide support for the float when there is less than a predeterminedamount of contrast media in the drip chamber, the seat and float formingan air tight seal between the drip chamber and the outlet of the buretteto prevent the passage of air into the outlet of the burette when thereis less than a predetermined amount of fluid in the drip chamber,wherein the seat includes one or more fluid passageways providing accessto the lower surface of the float such that the fluid in the dripchamber can contact a sufficient portion of the lower surface of thefloat to allow the buoyancy of the float to cause separation between thefloat and the seat when there is more than a predetermined amount offluid in the drip chamber to allow the fluid to flow from the dripchamber into the outlet of the burette.
 2. The float and seat assemblyof claim 1, wherein the seat comprises a plurality of projections. 3.The float and seat assembly of claim 2, wherein the plurality of fluidpassageways are positioned between the plurality of projections.
 4. Thefloat and seat assembly of claim 3, wherein the contrast media flowsthrough the fluid passageways between the plurality of projections tocontact the lower surface of the float.
 5. The float and seat assemblyof claim 1, wherein the lower surface of the float is comprised of amaterial that has a predetermined amount of deformability.
 6. The floatand seat assembly of claim 5, wherein the deformability of the materialcomprising the lower convex surface of the float is configured toconform to the seat to provide an air tight seal with the seat.
 7. Thefloat and seat assembly of claim 1, wherein the lower surface of thefloat has a relief that conforms to a relief of an upper contact surfaceof the seat.
 8. The float and seat assembly of claim 7, wherein the seatincludes a drainage bore positioned between the drip chamber and theoutlet of the burette.
 9. The float and seat assembly of claim 8,wherein the seat is configured to position the float in a level mannersuch that the lower surface of the float contacts a circumferentialcontact surface of the drainage bore in an air tight manner.
 10. Thefloat and seat assembly of claim 1, wherein the substantially ellipticalshape of the side profile of the float includes a substantially flatcircumferential rim which provides the desired amount of displacementbetween the upper convex surface and the lower convex surface.
 11. Thefloat and seat assembly of claim 10, wherein the seat forms a concavecontact surface to support the lower convex surface of the float.
 12. Aturbulence minimization apparatus for use with a burette of a contrastmedia delivery system, the burette including an inlet, a drip chamber,and an outlet, the turbulence minimization apparatus adapted to controlturbulence and the formation of microbubbles in a quantity of contrastmedia in the drip chamber, the turbulence minimization apparatuscomprising: a float positioned in the drip chamber of the burette, thefloat having an upper convex surface, a lower convex surface, and anouter circumferential rim positioned between the upper convex surfaceand the lower convex surface providing a desired amount of displacementbetween the upper convex surface and the lower convex surface, thejuxtaposition of the upper convex surface, the lower convex surface andthe outer circumferential rim forming a disk shaped configuration of thefloat such that the side profile of the float forms a substantiallyelliptical shape rather than a spherical shape or cylindrical, the floathaving a predetermined amount of buoyancy; and a seat configured toaccommodate and provide a concave support surface for the lower convexsurface of the float when there is less than a predetermined amount ofcontrast media in the drip chamber, the seat and float forming a fluidtight seal between the drip chamber and the outlet of the burette toprevent the passage of air into the outlet of the burette when there isless than a predetermined amount of fluid in the drip chamber, whereinthe seat includes one or more fluid passageways providing access to thelower surface of the float such that the fluid in the drip chamber cancontact a substantial portion of the lower surface of the float to allowthe buoyancy of the float to overcome a vacuum effect between the floatand the seat when there is more than a predetermined amount of fluid inthe drip chamber to allow the fluid to flow from the drip chamber intothe outlet of the burette.
 13. The turbulence minimization apparatus ofclaim 12, wherein the upper convex surface provides an impact surfacefor droplets falling from the inlet of the burette.
 14. The turbulenceminimization apparatus of claim 13, wherein the seat comprises aplurality of projections.
 15. The turbulence minimization apparatus ofclaim 14, wherein each of the plurality of projections include a contactsurface configured to accommodate and support the lower convex surfaceof the float.
 16. The turbulence minimization apparatus of claim 15,wherein the contact surfaces of the plurality of projectionscollectively comprise the concave support surface of the seat.
 17. Theturbulence minimization apparatus of claim 16, wherein the seat includesa drainage bore having a circumferential contact surface configured tocontact the lower convex surface of the float.
 18. The turbulenceminimization apparatus of claim 17, wherein the circumferential contactsurface and the lower convex surface of the float form an air tight sealfor preventing air from entering into the drainage bore when thecontrast media in the drip chamber is substantially drained from theburette.
 19. The turbulence minimization apparatus of claim 17, whereinthe circumferential contact surface is positioned at substantially thesame level as the inner portion of the plurality of projectionsimmediately adjacent the circumferential contact surface.
 20. Aturbulence minimization apparatus adapted to control turbulence and theformation of microbubbles in a quantity of contrast media in a chamberof a burette of a contrast media delivery system, the turbulenceminimization apparatus being configured to seal an outlet of the burettewhen the volume of contrast media in the chamber of the burette fallsbelow a predetermined level to minimize the introduction of air into adelivery line of the contrast media delivery system downstream from theoutlet of the burette, the turbulence minimization apparatus comprising:a float positioned in the chamber of the burette, the float having anupper convex surface, a lower convex surface, and an outercircumferential rim positioned between the upper convex surface and thelower convex surface providing a desired amount of displacement betweenthe upper convex surface and the lower convex surface, the juxtapositionof the upper convex surface, the lower convex surface and the outercircumferential rim forming a disk shaped configuration of the floatsuch that the side profile of the float forms a substantially ellipticalshape rather than a spherical shape or cylindrical, the float having apredetermined amount of buoyancy; and a seat assembly configured to bepositioned on the bottom of the burette in fluid connection with theoutlet of the burette, the seat assembly comprising: drainage borepositioned in the center of the seat assembly, the drainage bore beingin fluid connection with the outlet of the burette; and a seat having anupper surface configured to accommodate the lower convex surface of thefloat, wherein the seat includes a plurality of fluid passagewaysconfigured to allow the contrast media to contact at least a portion ofthe lower convex surface of the float, and wherein the lower convexsurface of the float provides a fluid tight seal with the drainage borewhen the lower convex surface of the seat is in position with the uppersurface of the seat.
 21. The turbulence minimization apparatus of claim20, wherein the fluid passageways comprise a plurality of apertures. 22.The turbulence minimization apparatus of claim 20, wherein the aperturesare formed through the upper surface of the seat forming a conduit frombeneath the seat to the lower surface of the float.
 23. The turbulenceminimization apparatus of claim 20, wherein the fluid passagewayscomprise channels.
 24. The turbulence minimization apparatus of claim23, wherein the channels are formed along the upper surface of the seat.25. The turbulence minimization apparatus of claim 20, wherein the seatcomprises a plurality of projections and the fluid passageways comprisethe spaces between the projections.
 26. The turbulence minimizationapparatus of claim 20, wherein the lower surface of the float comprisesa lower convex surface and the upper surface of the seat comprises anupper concave surface which mirrors the lower convex surface of thefloat.
 27. The turbulence minimization apparatus of claim 20, whereinthe buoyancy of the float results from the material from which the floatis comprised.
 28. The turbulence minimization apparatus of claim 20,wherein the buoyancy of the float results from an air cavity positionedbetween the upper surface and lower surface of the float.
 29. Theturbulence minimization apparatus of claim 20, wherein the buoyancy ofthe float results from a combination of an air cavity internal to thefloat and the material from which the float is comprised.